[C++11] Add range based accessors for the Use-Def chain of a Value.

This requires a number of steps.
1) Move value_use_iterator into the Value class as an implementation
   detail
2) Change it to actually be a *Use* iterator rather than a *User*
   iterator.
3) Add an adaptor which is a User iterator that always looks through the
   Use to the User.
4) Wrap these in Value::use_iterator and Value::user_iterator typedefs.
5) Add the range adaptors as Value::uses() and Value::users().
6) Update *all* of the callers to correctly distinguish between whether
   they wanted a use_iterator (and to explicitly dig out the User when
   needed), or a user_iterator which makes the Use itself totally
   opaque.

Because #6 requires churning essentially everything that walked the
Use-Def chains, I went ahead and added all of the range adaptors and
switched them to range-based loops where appropriate. Also because the
renaming requires at least churning every line of code, it didn't make
any sense to split these up into multiple commits -- all of which would
touch all of the same lies of code.

The result is still not quite optimal. The Value::use_iterator is a nice
regular iterator, but Value::user_iterator is an iterator over User*s
rather than over the User objects themselves. As a consequence, it fits
a bit awkwardly into the range-based world and it has the weird
extra-dereferencing 'operator->' that so many of our iterators have.
I think this could be fixed by providing something which transforms
a range of T&s into a range of T*s, but that *can* be separated into
another patch, and it isn't yet 100% clear whether this is the right
move.

However, this change gets us most of the benefit and cleans up
a substantial amount of code around Use and User. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203364 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth
2014-03-09 03:16:01 +00:00
parent b033b03c23
commit 36b699f2b1
100 changed files with 920 additions and 1075 deletions

View File

@@ -5580,9 +5580,8 @@ void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,
/// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
/// value is equal or not-equal to zero.
static bool IsOnlyUsedInZeroEqualityComparison(const Value *V) {
for (Value::const_use_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) {
if (const ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
for (const User *U : V->users()) {
if (const ICmpInst *IC = dyn_cast<ICmpInst>(U))
if (IC->isEquality())
if (const Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
if (C->isNullValue())
@@ -7326,12 +7325,10 @@ static bool isOnlyUsedInEntryBlock(const Argument *A, bool FastISel) {
return A->use_empty();
const BasicBlock *Entry = A->getParent()->begin();
for (Value::const_use_iterator UI = A->use_begin(), E = A->use_end();
UI != E; ++UI) {
const User *U = *UI;
for (const User *U : A->users())
if (cast<Instruction>(U)->getParent() != Entry || isa<SwitchInst>(U))
return false; // Use not in entry block.
}
return true;
}